Weighing scale



Sept. 3, 1940. G. M. RICHARD 2,213,594v

WEIGHING SCALE Filed May 11, 1938" INVENTOR ATTORNEYS Patented Sept. 3, 1940 WEIGHING SCALE Application May 11, 1938, Serial No. 207,240

Claims.

This invention relates generally to weighing scales, and more particularly to mechanically set pivots in the levers of such weighing scales.

The operation of mechanically inserting pivots 5 in scale levers of the type referred to by machining a taper on a portion of the pivot and driving it into a taper reamed hole in the lever is well known, it being described in detail in U. S. Patent 1,459,449 to H. O. I-Iem. Such tapered pivot construction when correctly fitted results in a very firmly seated pivot but it is expensive; the proper diameter must be determined by frequently fitting the tapered pivot since a hole may spoil the entire lever.

The object of the present invention is the provision of improved, inexpensive means for mechanically setting pivots in levers.

A further object is the provision of a scale pivot having a cylindrical body portion adapted to be inserted into a reamed hole having parallel sides.

Another object is the provision of improved key locking means adapted to be inserted into 25 a groove in the pivot body and to cut its own seat in the body of the lever.

These, and other objects and advantages will be apparent from the following description in which reference is had to the accompanying drawing, illustrating a preferred embodiment of the invention and in which similar reference numerals refer to similar parts throughout the several views.

In the drawing:

Fig. I is a perspective View of the end of a lever equipped according to theinvention.

Fig. H is an enlarged fragmentary view. of the locking means sectioned substantially along the line IIII of Figure III.

Fig. III is an enlarged fragmentary end view of the locln'ng means showing the end contour of the key in greater detail; and,

Fig. IV is a perspective fragmentary view of a modified form of pivot.

Referring to the drawing in detail, and particularly to the form shown in Figures I to III inclusive, the pivot H, according to the invention, comprises a substantially cylindrical body 62 having portions 53 and id adjacent its ends, which are machined to form knife edges [5 for engagement with the usual hardened scale bear-- ings (not shown). For the purpose of locking the pivot l i in a lever iii a longitudinally extending rectangular slot I l is milled into the cylindri- 55 cal body of the pivot ii. p This slot I1 is radially that is a few thousandths of an inch too large spaced from a plane passing vertically through the knife edge [5 and is adapted to receive a key i8. This key if! is longitudinally tapered and the tapered face is V milled forming sharp cutting edges I9. The key is preferably made from steel and hardened. The lever i5 is provided with a plurality of bores 26, in spaced relation to each other in a manner well known. When the pivot H is positioned in one of the bores 29, and its knife edge 15 is properly located, the 10 key I8 is inserted into the slot ll and driven inwardly so that the sharp edges l9 cut into the softer metal of the lever body and firmly lock the pivot against rotation. The metal displaced by the edges l9 mostly moves into the V groove. 15 The wedging effect, which is caused when the key i8 is driven against its taper, securely holds the pivot against longitudinal displacement. In some installations, especially in scales of higher capacities, it may be desirable to drive a similar 20 key l8 into the lever bore from the opposite side.

In scales having very high capacityit is 00-- casionally desirable, for the sake of economy, to make the body l2a of the pivot Ha from a comparatively inexpensive low carbon steel and drive hardened knife edge portions l5a, made from high grade steel, into slots 2! cut into the pivot body for this purpose. This modified form of pivot, as shown in Figure IV, is securely locked into the lever lfia in a similar manner by keys Ma.

From the aforegoing description it will be appreciated that among others the objects of the invention as specifically aforenoted are achieved.

It is to be understood, however, that the invention is susceptible to variations, modification and change within the spirit and scope of the subjoined claims. I

Having described the invention, I claim:

1. In a weighing scale, in combination, a lever, a supporting pivot seated in a cylindrical bore in said lever, said pivot comprising a cylindrical body portion, milled portions adjacent each end of said body portion forming pivot edges, there being a substantially rectangular slot in said body portion extending substantially parallel to a plane passing through said knife edges, and a key seated in said rectangular slot for locking said pivot in said lever, said key being substantially rectangular in cross section, one of its sides being tapered in respect to the opposite side and said tapering side being V milled to form a plurality of sharp edges, said sharp edges cutting into the body of said lever.

2. In a device of the class described, in combination, a lever having a smooth cylindrical bore, a pivot retainer having a cylindrical body portion received in said bore and a knife-edge portion extending from said cylindrical body portion, said cylindrical body portion having a key groove extending parallel to its axis, and a key seated in said groove and having a pair of cutting edges to cut a seat along said smooth cylindrical bore in said lever, said key having a space between said cutting edges to receive metal displaced by them in cutting a seat in said lever.

3. In a device of the class described, in combination, a lever having a smooth cylindrical bore," a pivot having a smooth cylindrical body portion fitting within said bore and a knife-edge extending from said body portion, said smooth cylindrical body portion being adapted for preliminary rotational and longitudinal adjustment within said bore to properly position said knife-edge, said cylindrical body portion having a keyway therein and'a tapered key having a cutting edge driven into said keyway and cutting its own seat along said bore and fixing said body portion within said bore in a selected position of rotational and longitudinal adjustment.

4. In a device of the class described, in combination, a lever having a smooth cylindrical bore, a pivot having a smooth cylindrical body portion and a knife-edge extending from said body portion, said smooth cylindrical body portion fitting within said bore and being adapted for rotational and longitudinal adjustment therein to properly position said knife-edge, said cylindrical body portion having a keyway therein and a key having parallel sides and a V-groove therebetween whereby cutting edges are formed along said parallel sides, said key being driven into said keyway and cutting its own seat along said bore and serving to fix said pivot to said lever with said I knife-edge in adjusted position.

5. In a device of the class described, in combination, a lever having a smooth cylindrical bore extending therethrough, a pivot having a cylindrical body portion and knife-edges extending from each end of said cylindrical body portion, said cylindrical body portion fitting within said bore and being adapted for preliminary rtational and longitudinal adjustment therein to properly position said knife-edges, said cylindrical body portion having key receiving ways extending parallel to its axis, and a pair of keys having cutting edges, said keys being driven along said ways into each end of said bore and cutting their own seats along said bore to fix said pivot to said lever with said knife-edges in adjusted positions.

GRANT M. RICHARD. 

